Long-term climate variability ‘could fall’ as the world warms

Long-term climate variability is the range of temperatures and weather patterns experienced by the Earth over a scale of thousands of years. New research suggests it could fall as the world warms.

A study using data taken from fossils and ice cores finds that long-term temperature variability decreased four-fold from the Last Glacial Maximum (LGM) around 21,000 years ago to the start of the Holocene around 11,500 years ago. Within this period, natural processes caused the planet to warm by around 3-8C.

If future global emissions are not curbed, human-driven global warming could cause further large declines in long-term temperature variability, the lead author tells Carbon Brief, which may have far-reaching effects on the world’s seasons and weather.

However, it is still unclear how a decline in long-term variability could affect the frequency of extreme weather events, she adds. This is because the chances of an extreme event happening could be influenced by both short- and long-term climate variability, as well as global temperature rise.

Digging up the past

The new study, published in Nature, is the first to make a global assessment of how long-term temperature variability changed from the LGM to the Holocene.

During the LGM, the world’s last major ice age, snow covered much of Asia, Europe and North America. Yet, within a few thousand years, global temperatures rose by around 3-8C, causing the ice to thaw and the world to enter its current geological period, the Holocene.

The cause of this temperature rise is still disputed by scientists, but research suggests the natural release of large stores of CO2 from the world’s oceans may have played a role.